Rochester is a census-designated place (CDP) in Thurston County, Washington, United States. It was founded in 1852, and the 2020 census recorded its population at 6,064. According to the United States Census Bureau, the CDP has a total area of 2.3 square miles (6.0 square kilometers), all of it land. Rochester Schools had 2,105 students registered in 2021-22 School Year.

Rochester was platted in 1890, and named after Rochester, Indiana, the native home of a first settler. An prematurely variant proclaim was “Key”.

As of the census of 2000, there were 1,829 people, 647 households, and 505 families residing in the CDP. The population density was 790.2 people per square mile (305.7/km²). There were 677 housing units at an average density of 292.5/sq mi (113.2/km). The racial makeup of the CDP was 88.41% White, 0.16% African American, 1.69% Native American, 0.93% Asian, 0.11% Pacific Islander, 5.52% from new races, and 3.17% from two or more races. Hispanic or Latino of any race were 10.39% of the population. 12.8% were of German, 11.5% Irish, 7.8% American, 7.5% Norwegian, 5.6% English and 5.4% Scottish ancestry.

There were 647 households, out of which 41.6% had children under the age of 18 living in the appearance of them, 62.4% were married couples vibrant together, 9.9% had a female householder in the same way as no husband present, and 21.9% were non-families. 17.2% of all households were made stirring of individuals, and 5.7% had someone vivacious alone who was 65 years of age or older. The average household size was 2.83 and the average relations size was 3.14.